1. Technical Field of the Invention
The present invention relates to a technique for producing images used for electrophotographic digital copying machines or color printers and, more specifically, to an apparatus for producing images in which a driving accuracy of a photoreceptor drum and an intermediate transfer belt is improved and variations in revolving speed of these two parties are synchronized to improve a color matching accuracy.
2. Related Art
A technique of producing images applied to an MFP (Multi-Function Peripherals) apparatus of an intermediate transfer system is disclosed in Japanese Unexamined Patent Application Publication No. 9-222826 as an apparatus for producing images in the related art.
In this apparatus for producing images, resonance frequency oscillations of a drive system of a revolving body drive unit such as a photoreceptor drum are attenuated by a flywheel provided on a drive shaft of the photoreceptor drum.
The apparatus for producing images in the related art is generally provided with a revolving body drive unit 1 having a common drive motor as shown in FIG. 6. The revolving body drive unit 1 interlocks a motor output shaft 2a of a drive motor 2 with a belt drive shaft 4a of an intermediate transfer belt 4 via two-stage reduction gear train 3, and interlocks the motor output shaft 2a of the drive motor 2 with a drum drive shaft 5a of a photoreceptor drum 5 via a three-stage reduction gear train 6, so that the intermediate transfer belt 4 and the photoreceptor drum 5 are driven by the common drive motor 2. In other words, the revolving body drive unit 1 in the related art drives the intermediate transfer belt 4 and the photoreceptor drum 5 separately and independently.
In FIG. 6, reference numeral 7 designates a primary transfer unit and reference numeral 8 designates a secondary transfer unit. In FIG. 6, chain lines designate pitch circles of respective gears which constitute two-system multi-speed reduction gear trains 3, 6, respectively.
Therefore, variations in revolving speed of the intermediate transfer belt 4 and the photoreceptor drum 5 are not synchronized due to their individual driving, whereby there is a risk of generating jitter at a primary transfer position.
Although a motor drive force from the drive motor 2 is transmitted to a drive roller 4a of the intermediate transfer belt 4 via independent two-stage reduction gear train, since the belt drive system of the photoreceptor drum 5 and the drum drive system of the intermediate transfer belt 4 are independent from each other, the belt drive system is not affected by inertia of the flywheel, and hence the inertia moment is small. Therefore, the intermediate transfer belt 4 has a weakness for (has a tendency to follow) variations in load from the outside, is likely to cause unevenness of revolution, and is likely to generate the jitter. The term “jitter” means such phenomenon as drifting or unevenness (shading) of color due to fine variations in speed or unevenness of revolution of the intermediate transfer belt.